Plasma display panel and method for producing same

ABSTRACT

An MgO layer ( 8 ) including an MgO crystal causing a cathode-luminescence emission having a peak within a range from 230 nm to 250 nm upon being excited by electron beams is provided in a position facing a discharge cell (C) formed in the discharge space between the front glass substrate ( 1 ) and the back glass substrate ( 4 ).

TECHNICAL FIELD

This invention relates to plasma display panels and a method ofmanufacturing the plasma display panels.

BACKGROUND ART

A surface-discharge-type alternating-current plasma display panel(hereinafter referred to as “PDP”) has two opposing glass substratesplaced on either side of a discharge-gas-filled discharge space, rowelectrode pairs extending in the row direction and regularly arranged inthe column direction on one of the glass substrates, column electrodesextending in the column direction and regularly arranged in the rowdirection on the other glass substrate, and unit light emission areas(discharge cells) thus formed in matrix form in positions correspondingto the intersections between the row electrode pairs and the columnelectrodes in the discharge space.

Further, in the PDP, a magnesium oxide (MgO) film, which has thefunction of protecting the dielectric layer and the function of emittingsecondary electrons into the unit light emission area, is formed on aportion of a dielectric layer facing the unit light emission areas, thedielectric layer being provided for covering the row electrodes or thecolumn electrodes.

As a method for forming the MgO film in the manufacturing process forPDPs as described above, the adoption of a screen printing technique ofapplying a coating of a paste containing an MgO powder mixture onto adielectric layer is considered on the grounds of simplicity andconvenience as described in Japanese unexamined patent publication No.6-325696, for example.

However, in the case of using a paste containing a polycrystallinefloccule type magnesium oxide obtained by heat-treating and purifyingmagnesium hydroxide, to form an MgO film of the PDP by a screen printingtechnique as described in Japanese unexamined patent publication No.6-325696, the resulting discharge characteristics of the PDP are merelylargely equal to or slightly greater than those provided in the case ofusing an evaporation technique to form the magnesium oxide film.

An urgent need arising from this is to form an MgO film capable ofyielding a greater improvement in the discharge characteristics in thePDP.

An object of the present invention is to solve the problem associatedwith PDPs having a conventional magnesium oxide film formed therein asdescribed above.

DISCLOSER OF THE INVENTION

Problems to be Solved by the Invention

To attain the above object, a PDP according to the invention (inventiondescribed in claim 1), which is equipped with a front substrate and aback substrate facing each other across a discharge space, and with,between the front substrate and the back substrate, a plurality of rowelectrode pairs and a plurality of column electrodes extending in adirection intersecting the row electrode pairs to form unit lightemitting areas in the respective portions of the discharge spacecorresponding to the intersections with the row electrode pairs, ischaracterized by providing, on an area facing the unit light emittingarea between the front substrate and the back substrate, a magnesiumoxide layer that includes a magnesium oxide crystal causing acathode-luminescence emission having a peak within a wavelength range of200 nm to 300 nm upon being excited by electron beams.

The magnesium oxide layer provided in areas facing the discharge cellsincludes magnesium oxide crystals causing a cathode-luminescenceemission having a peak within a wavelength range of 200 nm to 300 nmupon excitation by electron beams. Thereby, the above PDP is improved inthe discharge characteristics such as the discharge probability and thedischarge delay in the PDP and thus is capable of providing satisfactorydischarge characteristics.

Further, to attain the aforementioned object, a method of manufacturinga PDP according to the invention (invention described in claim 18) is amethod of manufacturing a plasma display panel which is equipped with afront substrate and a back substrate facing each other across adischarge space, electrodes formed on at least one of the front and backsubstrates, a dielectric layer covering the electrodes, and a protectivelayer covering the dielectric layer, and is characterized by having aprocess of forming a magnesium oxide layer that includes a magnesiumoxide crystal causing a cathode-luminescence emission having a peakwithin a wavelength range of 200 nm to 300 nm upon being excited byelectron beams, in a position covering a required portion of thedielectric layer.

With the above method of manufacturing the PDPs, in between the frontsubstrate and the back substrate facing each other across the dischargespace of the PDP, on a required portion of the dielectric layer, themagnesium oxide layer covering the dielectric layer is formed ofmagnesium oxide crystals causing a cathode-luminescence emission havinga peak within a wavelength range of 200 nm to 300 nm upon excitation byelectron beams. Thereby, the discharge characteristics such as thedischarge probability and the discharge delay in the PDP are improvedand it becomes possible to provide satisfactory dischargecharacteristics.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a front view illustrating a first embodiment example of anembodiment of the invention.

FIG. 2 is a sectional view taken along the V1-V1 line in FIG. 1.

FIG. 3 is a sectional view taken along the V2-V2 line in FIG. 1.

FIG. 4 is a sectional view taken along the W1-W1 line in FIG. 1.

FIG. 5 is a SEM photograph of a magnesium oxide single crystal having acubic single-crystal structure.

FIG. 6 is a SEM photograph of a magnesium oxide single crystal having acubic polycrystal structure.

FIG. 7 is a graph showing the relationship between the particlediameters of magnesium oxide single crystals and the wavelengths of CLemission in the first embodiment example.

FIG. 8 is a graph showing the relationship between the particlediameters of magnesium oxide single crystals and the peak intensities ofCL emission at 235 nm in the same example.

FIG. 9 is a graph showing the state of the wavelength of CL emissionfrom the magnesium oxide layer formed by vapor deposition.

FIG. 10 is a graph showing the relationship between the discharge delayand the peak intensities of CL emission at 235 nm from the magnesiumoxide single crystals.

FIG. 11 is a graph showing the improved state of the dischargeprobability in the same example.

FIG. 12 is a table showing the improved state of the dischargeprobability in the same example.

FIG. 13 is a graph showing the improved state of the discharge delay inthe same example.

FIG. 14 is a table showing the improved state of the discharge delay inthe same example.

FIG. 15 is a graph showing the relationship between the particlediameters of magnesium oxide single crystals and the dischargeprobability in the same example.

FIG. 16 is a front view illustrating a second embodiment example of anembodiment of the invention.

FIG. 17 is a sectional view taken along the V3-V3 line in FIG. 16.

FIG. 18 is a sectional view taken along the W2-W2 line in FIG. 16.

FIG. 19 is a sectional view illustrating the state of a magnesium oxidelayer formed by a coating of a paste including magnesium oxide singlecrystals in the same example.

FIG. 20 is sectional view illustrating the state of a magnesium oxidelayer consisting of a powder layer formed by a deposition of magnesiumoxide single crystals in the same example.

FIG. 21 is a graph showing the comparison between the dischargeprobability of the magnesium oxide layer consisting of a powder layerformed by a deposition of magnesium oxide single crystals in the sameexample and the discharge probability in another example.

FIG. 22 is a front view illustrating a third embodiment example of anembodiment of the invention.

FIG. 23 is a sectional view taken along the V4-V4 line in FIG. 22.

FIG. 24 is a sectional view taken along the W3-W3 line in FIG. 22.

FIG. 25 is a sectional view illustrating the state of a crystallinemagnesium oxide layer formed on a thin-film magnesium layer in the sameexample.

FIG. 26 is sectional view illustrating the state of a thin-filmmagnesium layer formed on a crystalline magnesium layer in the sameexample.

FIG. 27 is a graph showing the comparison of the discharge delaycharacteristics between the case when a protective layer is constitutedonly of a magnesium oxide layer formed by vapor deposition and that whena protective layer has a double layer structure made up of a crystallinemagnesium layer and a thin-film magnesium layer formed by vapordeposition.

BEST MODE FOR CARRYING OUT THE INVENTION

This invention will be described below in detail on the basis ofembodiment examples illustrated in the drawings.

First Embodiment Example

FIGS. 1 to 4 illustrate a first embodiment example in an embodiment ofthe invention.

FIG. 1 is a schematic front view of the cell structure of asurface-discharge-type AC PDP in the first embodiment example. FIG. 2 isa sectional view taken along the V1-V1 line in FIG. 1, FIG. 3 is asectional view taken along the V2-V2 line in FIG. 1, and FIG. 4 is asectional view taken along the W1-W1 line in FIG. 1.

The PDP in FIGS. 1 to 4 has a plurality of row electrode pairs (X, Y)extending in the row direction (the right-left direction in FIG. 1) of afront glass substrate 1 and regularly arranged in the column direction(the up-down direction in FIG. 1) on the rear-facing face of the frontglass substrate 1 serving as the display surface.

A row electrode X is composed of T-shaped transparent electrodes Xaformed of a transparent conductive film made of ITO or the like, and ablack bus electrode Xb which is formed of a metal film and which extendsin the row direction of the front glass substrate 1 and is connected tothe narrow proximal ends of the transparent electrodes Xa.

A row electrode Y, likewise, is composed of: T-shaped transparentelectrodes Ya formed of a transparent conductive film made of ITO or thelike; a black bus electrode Yb which is formed of a metal film, andwhich extends in the row direction of the front glass substrate 1 and isconnected to the narrow proximal ends of the transparent electrodes Ya;and address-discharge transparent electrodes Yc each formed integrallywith the transparent electrode Ya to extend out from the proximal end ofthe transparent electrode Ya toward the opposite side of the buselectrode Yb from the transparent electrode Ya.

The row electrodes X and Y are arranged in alternate positions in thecolumn direction of the front glass substrate 1 (the vertical directionin FIG. 1 and the right-left direction in FIG. 2). The transparentelectrodes Xa and Ya, which are regularly spaced along the associatedbus electrodes Xb and Yb, each extend out toward their counterparts inthe row electrode pair, so that the wide distal ends of the transparentelectrodes Xa and Ya face each other across a discharge gap g of arequired width.

Then, an address-discharge transparent electrode Yc of the row electrodeY is placed between the bus electrode Yb of this row electrode Y and thebus electrode Xb of the row electrode X which is of the adjacent rowelectrode pair (X, Y) in the column direction and is positioned back toback with and away from the bus electrode Yb.

A display line L extending in the row direction is formed in each rowelectrode pair (X, Y).

A dielectric layer 2 is formed on the rear-facing face of the frontglass substrate 1 so as to cover the row electrode pairs (X, Y). Blackor dark colored first additional dielectric layers 3A projectingbackward (downward in FIG. 2) from the dielectric layer 2 are formed onthe rear-facing face of the dielectric layer 2 so as to each extend, inparallel to the back-to-back bus electrodes Xb and Yb of the adjacentrow electrode pairs (X, Y) in the row direction, along a positionopposite to these bus electrodes Xb and Yb and the area between theback-to-back bus electrodes Xb and Yb (the area in which theaddress-discharge transparent electrodes Yc).

Further, a second additional dielectric layer 3B projecting backward(downward in FIG. 2) from the first additional dielectric layer 3A isformed on a portion of the rear-facing face of the first additionaldielectric layer 3A opposite to the bus electrode Xb so as to extendparallel to the bus electrode Xb.

A protective layer, not diagrammed, made of magnesium oxide (MgO) coversthe surface of the rear-facing faces of the dielectric layer 2, firstadditional dielectric layers 3A and second additional dielectric layers3B.

The front glass substrate 1 is placed in parallel to the back glasssubstrate 4 across the discharge space, and on the face of the backglass substrate 4 facing toward the front glass substrate 1, a pluralityof column electrodes D are arranged in parallel to each other atpredetermined intervals so as to each extend in a direction at rightangles to the bus electrodes Xb, Yb (the column direction) throughpositions opposite to the paired transparent electrodes Xa and Ya ineach row electrode pair (X, Y).

Further, a column-electrode protective layer (dielectric layer) 5covering the column electrodes D is formed on the face of the back glasssubstrate 4 facing toward the front glass substrate 1. A partition unit6 shaped as described below in detail is formed on the column-electrodeprotective layer 5.

Specifically, when viewed from the front glass substrate 1, thepartition unit 6 is constituted of first lateral walls 6A each extendingin the row direction along a position opposite to the bus electrode Xbof each row electrode X, vertical walls 6B each extending in the columndirection in a strip between the transparent electrodes Xa, Ya which areregularly spaced along the associated bus electrodes Xb, Yb of the rowelectrodes X, Y, and second lateral walls 6C each extending parallel tothe first lateral wall 6A at a required interval along a positionopposite the bus electrode Yb of each row electrode Y.

Then, the height of the first lateral wall 6A, the vertical wall 6B andthe second lateral wall 6C is set equal to the distance between theprotective layer covering the rear-facing face of the second additionaldielectric layers 3B and the column-electrode protective layer 5covering the column electrodes D.

Thereby, the front-facing face (the upper face in FIG. 2) of the firstlateral walls 6A of the partition unit 6 is in contact with theprotective layer covering the second additional dielectric layers 3B.

The first lateral walls 6A, the vertical walls 6B and the second lateralwalls 6C of the partition unit 6 partition the space between the frontglass substrate 1 and the back glass substrate 4 into areas eachcorresponding to the paired transparent electrodes Xa and Ya oppositeeach other to form display discharge cells (first light-emission areas)C1. Further, part of the space, which is sandwiched between the firstlateral wall 6A and the second lateral wall 6C and is opposite to thearea between the back-to-back bus electrodes Xb and Yb of the rowelectrode pairs (X, Y) adjacent to each other, is partitioned by thevertical walls 6B to thereby form address discharge cells (second lightemission areas) C2 each alternating with the display discharge cells C1in the column direction.

The address discharge cell C2 is placed opposite the address-dischargetransparent electrode Yc of the row electrode Y.

Further, the display discharge cell C1 and the address discharge cellC2, which are adjacent to each other across the second lateral wall 6Cin the column direction, communicate with each other by means of aclearance r that is formed between the protective layer covering thefirst additional dielectric layer 3A and the second lateral wall 6C.

A phosphor layer 7 is formed on the surface of the column-electrodeprotective layer 5 and the side faces of the first lateral wall 6A, thevertical walls 6B and the second lateral wall 6C of the partition unit 6which face toward the discharge space in each display discharge cell C1,so as to cover approximately all the five faces. The arrangement of thecolors of the phosphor layers 7 is red (R), green (G) and blue (B) insequence in the row direction in the respective display discharge cellsC1.

In addition, a magnesium oxide (MgO) layer 8, which includes magnesiumoxide crystals causing a cathode-luminescence emission (CL emission)having a peak within a wavelength range of 200 nm to 300 nm uponexcitation by electron beams, as described later in detail, is formed onthe surface of the column-electrode protective layer 5 and the sidefaces of the first lateral wall 6A, the vertical walls 6B and the secondlateral wall 6C of the partition unit 6 which face toward the dischargespace in each address discharge cell C2, so as to cover approximatelyall the five faces.

The display discharge cells C1 and the address discharge cells C2 arefilled with a discharge gas including xenon.

The MgO layer 8 of the foregoing PDP is formed of the followingmaterials and by the following method.

Specifically, included among MgO crystals which are used as materialsfor forming the MgO layer 8 and cause CL emission having a peak within awavelength range of 200 nm to 300 nm upon being excited by an electronbeam, is, for example, a single crystal of magnesium which is obtainedby performing vapor-phase oxidation on magnesium steam generated byheating magnesium (this single crystal of magnesium is hereinafterreferred to as “vapor-phase MgO single crystal”). As the vapor-phase MgOsingle crystal, an MgO single crystal having a cubic single-crystalstructure as illustrated in the SEM photograph in FIG. 5, and an MgOsingle crystal having a structure of cubic crystals fitted to each other(i.e. a cubic polycrystal structure) as illustrated in the SEMphotograph in FIG. 6 are included for example.

The vapor-phase MgO single crystal contributes to an improvement of thedischarge characteristics such as a reduction in discharge delay asdescribed later.

Further, as compared with magnesium oxide obtained by other methods, thevapor-phase magnesium oxide single crystal has the features of being ofa high purity, taking a microscopic particle form, causing less particleagglomeration, and the like.

The vapor-phase MgO single crystal used in the embodiment example has anaverage particle diameter of 500 or more angstroms (preferably, 2000 ormore angstroms) based on a measurement using the BET method.

The MgO layer 8 is formed by use of a method such as screen printing,offset printing, dispenser technique, ink-jet technique, roll-coatingtechnique to apply coating of a paste including vapor-phase magnesiumoxide single crystals as described above to the surface of thecolumn-electrode protective layer 5 and the side faces of the firstlateral wall 6A, the vertical walls 6B and the second lateral wall 6C ofthe partition unit 6 facing toward the discharge space in each addressdischarge cell C2, or alternatively by use of a method such as sprayingtechniques, electrostatic spraying techniques to cause the vapor-phasemagnesium oxide single crystals to adhere to the same.

In the foregoing PDP, when an image is generated, after a resetdischarge is produced in the display discharge cell C1 and the addressdischarge cell C2, an address discharge is initiated between theaddress-discharge transparent electrode Yc of the row electrode and thecolumn electrode D in the address discharge cell C2.

Charged particles thus generated through the address discharge in theaddress discharge cell C2 are introduced through the clearance r betweenthe first additional dielectric layer 3A and the second lateral wall 6Cinto the display discharge cell C1. The display discharge cells C1(light emission cells) having wall charges generated due to the chargedparticles and the display discharge cells C1 (non-light emission cells)having no wall charge generated are distributed over the panel face inaccordance with the image to be formed.

Then, after the address discharge, a sustaining discharge is initiatedbetween the transparent electrode Xa and the transparent electrode Ya ofthe row electrode pair (X, Y) in each light emission cell, therebycausing the red (R), green (G) and blue (B) phosphor layers 7 to emitlight to form the image on the panel face.

The foregoing PDP is designed such that the address discharge isproduced in the address discharge cell C2 that is partitioned off fromthe display discharge cell C1 in which the sustaining discharge isproduced for causing the phosphor layer 7 to emit light. This makes itpossible to provide stable address-discharge characteristics because theaddress discharge has no chance of being subject to effects originatingin the phosphor layer, such as discharge characteristics varyingaccording to the color of the phosphor materials and variations in thethickness of the phosphor layers occurring in the manufacturing process.

Further, in the foregoing PDP, when the reset discharge is initiatedprior to the address discharge, a discharge occurs in the addressdischarge as well. At this point, because the MgO layer 8 is formed inthe address discharge cell C2, the priming effect caused by the resetdischarge lasts for a long time, thereby speeding up in the addressdischarge.

Further, in the foregoing PDP, because the MgO layer 8 is formed in theaddress discharge cell C2, as shown in FIGS. 7 and 8, the application ofelectron beam excites, in addition to a CL (cathode-luminescence)emission having a peak within a wavelength range of 300 nm to 400 nm, aCL emission having a peak within a wavelength range of 200 nm to 300 nm(in particular, around 235 nm, of 230 nm to 250 nm) from thelarge-particle-diameter vapor-phase MgO single crystals included in theMgO layer 8.

As shown in FIG. 9, the CL emission with a peak within a wavelengthrange of 200 nm to 300 nm (in particular, around 235 nm, of 230 nm to250 nm) is not excited from a MgO layer formed typically by vapordeposition, but only a CL emission having a peak wavelengths from 300 nmto 400 nm is excited.

Further, as seen from FIGS. 7 and 8, the greater the particle diameterof the vapor-phase MgO single crystal, the stronger the peak intensityof the CL emission having a peak within the wavelength range from 200 nmto 300 nm (in particular, 235 nm).

For the sake of reference, the BET specific surface area (s) is measuredby a nitrogen adsorption method, and the particle diameter (D_(BET)) ofthe vapor-phase MgO single crystals forming the MgO layer 8 iscalculated from the measured value by the following equation.D _(BET) =A/s×ρ,

where

A: shape count (A=6)

ρ: real density of magnesium.

FIG. 10 is a graph showing the correlation between the CL emissionintensities and the discharge delay.

It is seen from FIG. 10 that the discharge delay in the PDP is shortenedby the 235 nm CL emission excited from the MgO layer 8, and further, asthe intensity of the 235 nm CL emission increases, the discharge delayis shortened.

As described hitherto, the foregoing PDP is capable of providingsatisfactory discharge characteristics as a result of the formation ofthe MgO layer 8 including the vapor-phase MgO single crystals of anaverage particle diameter of 500 or more angstroms (preferably, 2000 ormore angstroms) measured by the BET method, for the purpose of animprovement of the discharge characteristics (a reduction in dischargedelay, an increase in the discharge probability).

FIG. 11 is a graph of the comparison of the discharge probabilities inthe cases where the MgO layer 8 to be provided in the address dischargecell C2 is formed by application of coating of a paste including thevapor-phase MgO single crystals of an average particle diameter rangingfrom 2000 to 3000 angstroms, where an MgO layer is formed byconventional vapor deposition techniques, and where no MgO layer isformed. FIG. 12 shows the discharge probabilities in the cases in FIG.11 when the rest time of the discharge is 1000 μsec.

Further, similarly, FIG. 13 is a graph of the comparison of thedischarge delay times in the cases where the MgO layer 8 is formed byapplication of a coating of a paste including the vapor-phase MgO singlecrystals of an average particle diameter ranging from 2000 to 3000angstroms, where an MgO layer is formed by conventional vapor depositiontechniques, and where no MgO layer is formed. FIG. 14 shows thedischarge delay times in the cases in FIG. 13 when the rest time of thedischarge is 1000 μsec.

Note that FIGS. 11 to 14 show the case where vapor-phase MgO singlecrystals of a polycrystal structure are included in the MgO layer 8.

It is seen from FIGS. 11 to 14 that the provision of the MgO layer 8including the vapor-phase MgO single crystals causes a significantimprovement in the discharge probability and the discharge delay in theforegoing PDP and further causes a reduction in the dependence ofdischarge delay on rest time, leading to satisfactory dischargecharacteristics.

FIG. 15 is a graph showing the relationship between the dischargeprobabilities and the particle diameters of the vapor-phase MgO singlecrystals forming the MgO layer 8.

It is seen from FIG. 15 that the greater the particle diameter of thevapor-phase MgO single crystal forming the MgO layer 8, the higher thedischarge probability, and the MgO layer 8, which is formed of thevapor-phase MgO single crystals of a particle diameter (2000 angstromsand 3000 angstroms in the examples shown in the figure) exciting a CLemission having a peak at 235 nm as described earlier, effects asignificant improvement in discharge probability.

More specifically, the conjectured reason for the improvement of thedischarge characteristics caused by the MgO layer 8 in the PDP asdescribed above is because the vapor-phase MgO single crystals causingthe CL emission having a peak within the wavelength range from 200 nm to300 nm (in particular, around 235 nm, of 230 nm to 250 nm) have anenergy level corresponding to the peak wavelength, so that the energylevel enables the trapping of electrons for a long time (some msec. ormore), and the trapped electrons are extracted by an electric field soas to serve as the primary electrons required for starting a discharge.

Also, because of the correlation between the intensity of the CLemission and the particle diameter of the vapor-phase MgO singlecrystals, the stronger the intensity of the CL emission having a peakwithin the wavelength range from 200 nm to 300 nm (in particular, around235 nm, of 230 nm to 250 nm), the greater the improvement effect of thedischarge characteristics caused by the vapor-phase MgO single crystal.

In other words, for the deposition of vapor-phase MgO single crystals ofa large particle diameter, an increase in the heating temperature forgenerating magnesium vapor is required. Because of this, the length ofthe flame with which magnesium and oxygen react increases, and thereforethe temperature difference between the flame and the surroundingambience increases. It is thus conceivable that the larger the particlesize of the vapor-phase MgO single crystal, the greater the number ofenergy levels occurring in correspondence with the peak wavelengths(e.g. around 235 nm, within a range from 230 nm to 250 nm) of the CLemission as described earlier.

In a further conjecture regarding the vapor-phase MgO single crystal ofa cubic polycrystal structure, many plane defects occur and the presenceof energy levels arising from these plane defects contributes to animprovement in discharge probability.

For the sake of reference, it is seen from FIG. 15 that the dischargeprobability is greatly enhanced even when the MgO layer 8 is formed bythe application of a coating of a paste including vapor-phase MgO singlecrystals of an average particle diameter of the order of 500 angstromsby use of a method such as a screen printing technique, an offsetprinting technique, a dispenser technique, an ink-jet technique or aroll-coating technique, as compared with that in conventionalvapor-deposited MgO layers.

Further, the above-described results in FIGS. 7 to 15 are obtained whenthe MgO layer 8 is formed by the application of a coating of a pasteincluding vapor-phase MgO single crystals by use of a method such as ascreen printing technique, a nozzle coating or an ink-jet technique, butthe MgO layer 8 may be formed of a powder layer resulting fromdeposition of the powder of vapor-phase MgO single crystals by use of amethod such as a spraying technique or an electrostatic coatingtechnique.

Further, the above embodiment example illustrates the case of formingthe MgO layer 8 by applying a coating of a paste including vapor-phasesingle crystals to the interior of the address discharge cell. However,a paste including MgO single crystals may be applied so as to cover thedielectric layer 2 provided on the front substrate to form a protectivelayer.

Further, a conventional MgO film may be formed on the dielectric layer 2on the front substrate by vapor deposition, and then the MgO film may becoated with a paste including the powder of vapor-phase MgO singlecrystals to form an MgO film as a second layer.

Second Embodiment Example

FIGS. 16 to 18 illustrate a second embodiment example of an embodimentof the PDP according to the invention. FIG. 16 is a schematic front viewof the PDP in the second embodiment example. FIG. 17 is a sectional viewtaken along the V3-V3 line in FIG. 16, and FIG. 18 is a sectional viewtaken along the W2-W2 line in FIG. 16.

The PDP shown in FIGS. 16 to 18 has a plurality of row electrode pairs(X1, Y1) arranged in parallel on a rear-facing face of a front glasssubstrate 10 serving as the display surface so as to extend in the rowdirection (the right-left direction in FIG. 16) of the front glasssubstrate 10.

A row electrode X1 is composed of T-shaped transparent electrodes X1 aformed of a transparent conductive film made of ITO or the like, and abus electrode X1 b which is formed of a metal film and which extends inthe row direction of the front glass substrate 10 and is connected tothe narrow proximal ends of the transparent electrodes X1 a.

A row electrode Y1, likewise, is composed of T-shaped transparentelectrodes Y1 a formed of a transparent conductive film made of ITO orthe like, and a bus electrode Y1 b which is formed of a metal film andwhich extends in the row direction of the front glass substrate 10 andis connected to the narrow proximal ends of the transparent electrodesY1 a.

The row electrodes X1 and Y1 are arranged in alternate positions in thecolumn direction of the front glass substrate 10 (the vertical directionin FIG. 16). The transparent electrodes X1 a and Y1 a, which areregularly spaced along the associated bus electrodes X1 b and Y1 b, eachextend out toward their counterparts in the row electrode pair, so thatthe wide distal ends of the transparent electrodes X1 a and Y1 a faceeach other across a discharge gap g1 of a required width.

Black or dark-colored light absorption layers (light-shield layers) 11are each formed on the rear-facing face of the front glass substrate 10between the back-to-back bus electrodes X1 b and Y1 b of the rowelectrode pairs (X1, Y1) adjacent to each other in the column direction,and extend along these bus electrodes X1 b, Y1 b in the row direction.

Further, a dielectric layer 12 is formed on the rear-facing face of thefront glass substrate 10 so as to cover the row electrode pairs (X1,Y1). On the rear-facing face of the dielectric layer 12, additionaldielectric layers 12A, which project backward from the dielectric layer12, are each formed in a position opposite to the back-to-back buselectrodes X1 b and Y1 b of the row electrode pairs (X1, Y1) adjacent toeach other and to the area between the above bus electrode X1 b and theabove bus electrode Y1 b positioned back to back, so as to extendparallel to the bus electrodes X1 b, Y1 b.

In turn, on the rear-facing faces of the dielectric layer 12 and theadditional dielectric layers 12A, an MgO layer 13, which includes MgOcrystals causing a CL emission having a peak within a wavelength rangeof 200 nm to 300 nm upon excitation by electron beams, as describedlater, is formed.

On the other hand, on the display-side face of the back glass substrate14 placed parallel to the front glass substrate 10, column electrodes D1are arranged in parallel to each other at predetermined intervals so asto extend in a direction at right angles to the row electrode pairs (X1,Y1) (the column direction) through positions opposite to the pairedtransparent electrodes X1 a and Y1 a in each row electrode pair (X1,Y1).

A white column-electrode protective layer 15 covering the columnelectrodes D1 is further formed on the display-side face of the backglass substrate 14, and in turn partition units 16 are formed on thecolumn-electrode protective layer 15.

Each of the partition units 16 is formed in a ladder shape made up of apair of transverse walls 16A extending in the row direction in therespective positions opposite to the bus electrodes X1 b and Y1 b ofeach row electrode pair (X1, Y1), and vertical walls 16B each extendingin the column direction between the pair of transverse walls 16A in amid-position between the adjacent column electrodes D1. The partitionunits 16 are regularly arranged in the column direction on either sideof an interstice SL which extends in the row direction between theback-to-back transverse walls 16A of the adjacent partition units 16.

Then, the ladder-shaped partition units 16 partition the discharge spaceS between the front glass substrate 10 and the back glass substrate 13into quadrangular areas each corresponding to the paired transparentelectrodes X1 a and Y1 a in each row electrode pair (X1, Y1) to formdischarge cells C3.

A phosphor layer 17 is formed on the side faces of the transverse walls16A and the vertical walls 16B of the partition unit 16 and the face ofthe column-electrode protective layer 15 which face toward eachdischarge cell C3, so as to cover all these five faces. The arrangementof the colors of the phosphor layers 17 is the three primary colors,red, green and blue, in sequence in the row direction in the respectivedischarge cells C3.

The MgO layer 13 covering the additional dielectric layers 12A is incontact with the display-side faces of the transparent walls 16A of thepartition units 16 (see FIG. 17), whereby each additional dielectriclayer 12A blocks off the discharge cell C3 and the interstice SL fromeach other. However, the display-side face of the vertical wall 16B isout of contact with the MgO layer 13 (see FIG. 18), to form a clearancer1 therebetween, so that the adjacent discharge cells C3 in the rowdirection communicate with each other by means of the clearance r1.

The discharge space S is filled with a discharge gas including xenon.

As in the case of the first embodiment example, included among MgOcrystals used for forming the MgO layer 13, is a single crystal obtainedby performing vapor-phase oxidation on magnesium steam generated byheating magnesium by a vapor-phase oxidation technique; for example, avapor-phase MgO single crystal causing CL emission having a peak withina wavelength range of 200 nm to 300 nm (in particular, 235 nm) uponbeing excited by an electron beam. As the vapor-phase MgO singlecrystal, an MgO single crystal having a cubic single crystal structureas illustrated in the SEM photograph in FIG. 5, and an MgO singlecrystal having a cubic polycrystal structure of cubic crystals fitted toeach other as illustrated in the SEM photograph in FIG. 6 are includedfor example.

Then, the MgO layer 13 is formed by use of a method such as screenprinting, offset printing, dispenser technique, ink-jet technique or aroll-coating technique to apply a coating of a paste includingvapor-phase MgO single crystals as described above to the surfaces ofthe dielectric layer 12 and the additional dielectric layers 12A, oralternatively by use of a method such as spraying techniques,electrostatic spraying techniques to cause the vapor-phase MgO singlecrystals to adhere to the surfaces of the dielectric layer 12 and theadditional dielectric layers 12A, or again by drying a coating of apaste including the vapor-phase MgO single crystal applied to a supportfilm to form a film or a sheet shape and then laminating the film orsheet on the dielectric layer.

FIG. 19 shows the state when the MgO layer 13(A) is formed by use of amethod such as screen printing, offset printing, dispenser technique,ink-jet technique or roll-coating technique to apply a coating of apaste including the vapor-phase MgO single crystals.

Similarly, FIG. 20 shows the state when the MgO layer 13(B) isconstituted of a powder layer formed by a deposition of powder ofvapor-phase MgO single crystals by use of a method such as a sprayingtechnique or electrostatic coating technique. In the foregoing PDP, thespeeding up of a discharge initiated in the discharge cell C3 (e.g. thespeeding up of an address discharge by the long continuation of thepriming effect resulting from a reset discharge) is achieved by formingan MgO layer 13 which includes MgO crystals causing CL emission having apeak within the wavelength from 200 nm to 300 nm upon being excited byelectron beams.

FIG. 21 is a graph of the comparison between the discharge delay time inthe case when a powder of MgO single crystals is dispersed in a mediumsuch as a specific alcohol and then the suspension is sprayed to thesurfaces of the dielectric layer 12 and the additional dielectric layers12A by an air spray method using a spray gun to deposit the powder ofMgO single crystals in order to form the MgO layer 13, and the dischargedelay times in other examples.

In FIG. 21, the graph a shows the discharge probabilities when a powderlayer formed of a powder of vapor-phase MgO single crystals of anaverage particle diameter of 500 angstroms is formed on the surface ofthe dielectric layer 12. The graph b shows the discharge probabilitieswhen a conventional vapor deposition technique is used to form an MgOlayer on the surface of the dielectric layer. The graph c shows thedischarge probabilities when, as described in the first embodimentexample, in a PDP of the type having the discharge cells each dividedinto a display discharge cell and an address discharge cell, an MgOlayer is formed in the address discharge cell by application of acoating of a paste including a powder of vapor-phase MgO single crystalsof an average particle diameter of 500 angstroms. The graph d shows thedischarge probabilities when in an address discharge cell of a similartype, an MgO layer is formed by a conventional vapor depositiontechnique.

It is seen from the comparison between the graphs a and c in FIG. 21that as regards the discharge probabilities (discharge delay) when theMgO layer 13 is constituted of a powder layer formed by a deposition ofa powder of vapor-phase MgO single crystals, it is possible to providethe characteristics approximately equal to those in the case when theMgO layer is formed by application of a coating of a paste including theMgO single crystals.

It is further seen that, as compared with the case of an MgO layerformed by using a conventional vapor deposition technique, the dischargeprobabilities are greatly improved, either when, by use of thevapor-phase MgO single crystals of an average particle diameter of 500angstroms, a coating is applied by a method such as screen printing,offset printing, dispenser technique, ink-jet technique or roll-coatingtechnique to form an MgO layer, or when an MgO layer is formed bydeposition using a method such as a spraying technique or electrostaticcoating technique.

Third Embodiment Example

FIGS. 22 to 24 illustrate a third embodiment example of an embodiment ofthe PDP according to the invention. FIG. 22 is a schematic front view ofthe PDP in the third embodiment example. FIG. 23 is a sectional viewtaken along the V4-V4 line in FIG. 22, and FIG. 24 is a sectional viewtaken along the W3-W3 line in FIG. 22.

The PDP shown in FIGS. 22 to 24 has a plurality of row electrode pairs(X2, Y2) arranged in parallel on a rear-facing face of a front glasssubstrate 21 serving as the display surface so as to extend in the rowdirection (the right-left direction in FIG. 22) of the front glasssubstrate 21.

A row electrode X2 is composed of T-shaped transparent electrodes X2 aformed of a transparent conductive film made of ITO or the like, and abus electrode X2 b which is formed of a metal film and which extends inthe row direction of the front glass substrate 21 and is connected tothe narrow proximal ends of the transparent electrodes X2 a.

A row electrode Y2, likewise, is composed of T-shaped transparentelectrodes Y2 a formed of a transparent conductive film made of ITO orthe like, and a bus electrode Y2 b which is formed of a metal film andwhich extends in the row direction of the front glass substrate 21 andis connected to the narrow proximal ends of the transparent electrodesY2 a.

The row electrodes X2 and Y2 are arranged in alternate positions in thecolumn direction of the front glass substrate 21 (the vertical directionin FIG. 22). The transparent electrodes X2 a and Y2 a, which areregularly spaced along the associated bus electrodes X2 b and Y2 b, eachextend out toward their counterparts in the row electrode pair, so thatthe wide distal ends of the transparent electrodes X2 a and Y2 a faceeach other across a discharge gap g2 of a required width.

Black or dark-colored light absorption layers (light-shield layers) 22are each formed on the rear-facing face of the front glass substrate 21between the back-to-back bus electrodes X2 b and Y2 b of the rowelectrode pairs (X2, Y2) adjacent to each other in the column direction,and extend along these bus electrodes X2 b, Y2 b in the row direction.

Further, a dielectric layer 23 is formed on the rear-facing face of thefront glass substrate 21 so as to cover the row electrode pairs (X2,Y2). On the rear-facing face of the dielectric layer 23, additionaldielectric layers 23A, which project backward from the dielectric layer23, are each formed in a position opposite to the back-to-back buselectrodes X2 b and Y2 b of the row electrode pairs (X2, Y2) adjacent toeach other and to the area between the above bus electrode X2 b and theabove bus electrode Y2 b positioned back to back, so as to extendparallel to the bus electrodes X2 b, Y2 b.

In turn, on the rear-facing faces of the dielectric layer 23 and theadditional dielectric layers 23A, an MgO layer (hereinafter referred toas “thin-film MgO layer”) 24 of a thin film formed by vapor depositionor spattering is formed and covers the rear-facing faces of thedielectric layer 23 and the additional dielectric layers 23A.

An MgO layer (hereinafter referred to as “crystalline MgO layers”) 25including MgO crystals causing a cathode-luminescence emission (CLemission) having a peak within a wavelength range of 200 nm to 300 nm(in particular, around 235 nm, of 230 nm to 250 nm) upon excitation byelectron beams as described in detail later is formed on the rear-facingface of the thin-film MgO layer 24.

The crystalline MgO layer 25 is formed on either the entire rear-facingface or a part of the rear-facing face of the thin-film MgO layer 24,for example a part facing a discharge cell which will be described later(in the example illustrated in the figures, the crystalline MgO layer 25is formed on the entire rear-facing face of the thin-film MgO layer 24).

On the other hand, on the display-side face of the back glass substrate26 placed parallel to the front glass substrate 21, column electrodes D2are arranged in parallel to each other at predetermined intervals so asto extend in a direction at right angles to the row electrode pairs (X2,Y2) (the column direction) through positions opposite to the pairedtransparent electrodes X2 a and Y2 a in each row electrode pair (X2,Y2).

A white column-electrode protective layer (dielectric layer) 27 coveringthe column electrodes D2 is further formed on the display-side face ofthe back glass substrate 26, and in turn partition units 28 are formedon the column-electrode protective layer 27.

Each of the partition units 28 is formed in a ladder shape made up of apair of transverse walls 28A extending in the row direction in therespective positions opposite to the bus electrodes X2 b and Y2 b ofeach row electrode pair (X2, Y2), and vertical walls 28B each extendingin the column direction between the pair of transverse walls 28A in amid-position between the adjacent column electrodes D2. The partitionunits 28 are regularly arranged in the column direction on either sideof an interstice SL which extends in the row direction between theback-to-back transverse walls 28A of the adjacent partition units 28.

Then, the ladder-shaped partition units 28 partition the discharge spaceS1 between the front glass substrate 21 and the back glass substrate 26into quadrangles respectively corresponding to discharge cells C4 formedin relation to the paired transparent electrodes X2 a and Y2 a in eachrow electrode pair (X2, Y2).

A phosphor layer 29 is formed on the side faces of the transverse walls28A and the vertical walls 28B of the partition unit 28 and the face ofthe column-electrode protective layer 27 which face toward the dischargespace S1, so as to cover all these five faces. The arrangement of thecolors of the phosphor layers 29 is the three primary colors, red, greenand blue, in sequence in the row direction in the respective dischargecells C4.

The crystalline MgO layer 25 (or the thin-film MgO layer 24 if thecrystalline MgO layer 25 is formed only a portion of the rear-facingface of the thin-film MgO layer 24 facing each discharge cell C4)covering the additional dielectric layers 23A is in contact with thedisplay-side faces of the transparent walls 28A of the partition units28 (see FIG. 23), whereby each additional dielectric layer 23A blocksoff the discharge cell C4 and the interstice SL from each other.However, the crystalline MgO layer 25 (or the thin-film MgO layer 24) isout of contact with the display-side face of the vertical wall 28B (seeFIG. 24), to form a clearance r2 therebetween, so that the adjacentdischarge cells C4 in the row direction communicate with each other bymeans of the clearance r2.

The discharge space S1 is filled with a discharge gas including xenon.

The crystalline MgO layer 25 is formed by depositing MgO crystals, asdescribed earlier, to the surface of the rear-facing face of thethin-film MgO layer 24 covering the dielectric layer 23 and theadditional dielectric layers 23A by a method such as a sprayingtechnique or electrostatic coating technique.

Note that the embodiment example describes the case where the thin-filmMgO layer 24 is formed on the rear-facing faces of the dielectric layer23 and the additional dielectric layers 23A and then the crystalline MgOlayer 25 is formed on the rear-facing face of the thin-film MgO layer24. However, the thin-film MgO layer 24 may be formed on the rear-facingface of the crystalline MgO layer 25 after the crystalline MgO layer 25may be formed on the rear-facing faces of the dielectric layer 23 andthe additional dielectric layers 23A.

FIG. 25 illustrates the state when the thin-film MgO layer 24 is formedon the rear-facing face of the dielectric layer 23 and then MgO crystalsare deposited to the rear-facing face of the thin-film MgO layer 24 toform the crystalline MgO layer 25 by use of a method such as a sprayingtechnique or electrostatic coating technique.

Also, FIG. 26 illustrates the state when MgO crystals are deposited tothe rear-facing face of the dielectric layer 23 to form the crystallineMgO layer 25 by use of a method such as a spraying technique orelectrostatic coating technique, and then the thin-film MgO layer 24 isformed.

The crystalline MgO layer 25 of the foregoing PDP is formed by use ofthe following materials and method.

Specifically, included among MgO crystals which are used as materialsfor forming the crystalline MgO layer 25 and causes CL emission having apeak within a wavelength range of 200 nm to 300 nm (in particular,around 235 nm, of 230 nm to 250 nm) upon being excited by an electronbeam, is, for example, a single crystal of magnesium obtained byperforming vapor-phase oxidation on magnesium steam generated by heatingmagnesium (this single crystal of magnesium is hereinafter referred toas “vapor-phase MgO single crystal”), as in the cases of the foregoingfirst and second embodiment examples. As the vapor-phase MgO singlecrystal, an MgO single crystal having a cubic single crystal structureas illustrated in the SEM photograph in FIG. 5, and an MgO singlecrystal having a structure of cubic crystals fitted to each other (i.e.a cubic polycrystal structure) as illustrated in the SEM photograph inFIG. 6 are included for example.

The vapor-phase MgO single crystal contributes to an improvement of thedischarge characteristics such as a reduction in discharge delay asdescribed later.

Further, as compared with MgO obtained by other methods, the vapor-phaseMgO single crystal has the features of being of a high purity, taking amicroscopic particle form, causing less particle agglomeration, and thelike.

The vapor-phase MgO single crystal used in the embodiment example has anaverage particle diameter of 500 or more angstroms (preferably, 2000 ormore angstroms) based on a measurement using the BET method.

For the sake of reference, the preparation of the vapor-phase MgO singlecrystal is described in “Preparation of magnesia powder using a vaporphase method and its properties” (“Zairyou (Materials)” vol. 36, no.410, pp. 1157-1161, the November 1987 issue), and the like.

The crystalline MgO layer 25 is formed, for example, by depositing thevapor-phase MgO single crystal by use of a method such as a sprayingtechnique or electrostatic coating technique, as described earlier.

In the above-mentioned PDP, a reset discharge, an address discharge anda sustaining discharge for generating an image are produced in thedischarge cell C4.

Then, when the reset discharge is initiated in the discharge cell C4prior to the initiation of the address discharge, the priming effectresulting from the reset discharge lasts for a long time because of theformation of the crystalline MgO layer 25 in the discharge cell C4,thereby speeding up of the address discharge.

In the above PDP, as illustrated in FIGS. 7 and 8 described earlier, thecrystalline MgO layer 25 is formed of a vapor-phase MgO single crystalas described above, whereby the application of electron beams caused bythe discharge excites, in addition to a CL emission having a peak withina wavelength range of 300 nm to 400 nm, a CL emission having a peakwithin a wavelength range of 200 nm to 300 nm (in particular, around 235nm, of 230 nm to 250 nm) from the large-particle-diameter vapor-phaseMgO single crystals included in the crystalline MgO layer 25. Thegreater the particle diameter of the vapor-phase MgO single crystal, thestronger the peak intensity of the CL emission having a peak within thewavelength range from 200 nm to 300 nm (in particular, around 235 nm, of230 nm to 250 nm).

As shown in FIG. 9 described earlier, the CL emission with a peak at 235nm is not excited from a MgO layer formed typically by vapor deposition(corresponding to the thin-film MgO layer 24 in this embodimentexample), but only a CL emission having a peak wavelengths from 300 nmto 400 nm is excited.

It is conjectured that the presence of the CL emission having the peakwavelength from 200 nm to 300 nm will effect a further improvement ofthe discharge characteristics (a reduction in discharge delay, anincrease in the probability of a discharge).

More specifically, the conjectured reason for the improvement of thedischarge characteristics caused by the crystalline MgO layer 25 isbecause the vapor-phase MgO single crystals causing the CL emissionhaving a peak within the wavelength range from 200 nm to 300 nm (inparticular, around 235 nm, of 230 nm to 250 nm) have an energy levelcorresponding to the peak wavelength, so that the energy level enablesthe trapping of electrons for a long time (some msec. or more), and thetrapped electrons are extracted by an electric field so as to serve asthe primary electrons required for starting a discharge.

Therefore, the reason that the stronger the intensity of the CL emissionhaving a peak within the wavelength range from 200 nm to 300 nm (inparticular, around 235 nm, of 230 nm to 250 nm), the greater theimprovement effects of the discharge characteristics caused by thevapor-phase MgO single crystal is as described in the aforementionedfirst embodiment example.

For the sake of reference, the particle diameter (D_(BET)) of thevapor-phase MgO single crystals forming the crystalline MgO layer 25 iscalculated by the same method as that in the first embodiment example.

The correlation between the CL emission intensities and the dischargedelay is, as is the case shown in FIG. 10 in the first embodimentexample, that the display delay in the PDP is shortened by the 235 nm CLemission excited from the crystalline MgO layer 25, and further, as theintensity of the 235 nm CL emission increases, the discharge delay isshortened.

FIG. 27 shows the comparison of the discharge delay characteristicsbetween the case of the PDP having the double-layer structure of thethin-film MgO layer 24 and the crystalline MgO layer 25 as describedabove (Graph a), and the case of a conventional PDP having only a MgOlayer formed by vapor deposition (Graph b).

As seen from FIG. 27, it is seen that a PDP is provided with thedouble-layer structure of the thin-film MgO layer 24 and the crystallineMgO layer 25, whereby the discharge delay characteristics issignificantly improved as compared with a conventional PDP having only athin-film MgO layer formed by vapor deposition.

As described hitherto, by forming the crystalline MgO layers 25including MgO crystals causing a CL emission having a peak within awavelength range from 200 nm to 300 nm upon being excited by an electronbeam in addition to the conventional thin-film MgO layer 24 formed byvapor deposition or the like, the above-described PDP is improved in thedischarge characteristics such as the discharge delay, and is capable ofshowing satisfactory discharge characteristics.

As the MgO crystals forming the crystalline MgO layer 25, an MgO crystalof an average particle diameter of 500 or more angstroms based on ameasurement using the BET method, preferably, of a range from 2000angstroms to 4000 angstroms, is used.

The crystalline MgO layer 25 is not necessary required to be formed soas to cover the entire face of the thin-film MgO layer 24 as describedearlier, and may be formed by patterning partially on portions facingthe transparent electrodes X2 a, Y2 a of the row electrodes X2, Y2 or onportions excepting portions facing the transparent electrodes X2 a, Y2a, for example.

When the crystalline MgO layer 25 is formed partially, the area ratio ofthe crystalline MgO layers 25 to the thin-film MgO layer 24 is set atfrom 0.1 to 85 percent.

For the sake of reference, the foregoing has described the case when thepresent invention applies to a reflection type AC PDP having the frontglass substrate on which row electrode pairs are formed and covered witha dielectric layer and the back glass substrate on which phosphor layersand column electrodes are formed. However, the present invention isapplicable to various types of PDPs, such as a reflection-type AC PDPhaving row electrode pairs and column electrodes formed on the frontglass substrate and covered with a dielectric layer, and having phosphorlayers formed on the back glass substrate; a transmission-type AC PDPhaving phosphor layers formed on the front glass substrate, and rowelectrode pairs and column electrodes formed on the back glass substrateand covered with a dielectric layer; a three-electrode AC PDP havingdischarge cells formed in positions corresponding to the intersectionsbetween row electrode pairs and column electrodes in the dischargespace; a two-electrode AC PDP having discharge cells formed in positionscorresponding to the intersections between row electrode pairs andcolumn electrodes in the discharge space.

Further, the foregoing has described the case when the crystalline MgOlayer 25 is formed through deposition by use of a method such as aspraying technique or an electrostatic coating technique. However, thecrystalline MgO layer 25 may be formed through application of a coatingof a paste including a powder of MgO crystals by use of a method such asa screen printing technique, an offset printing technique, a dispensertechnique, an ink-jet technique of a roll-coating technique, oralternatively may be formed by applying a paste including MgO crystalsto a support film, then drying it to a film and then laminating the filmon the thin-film MgO layer.

INDUSTRIAL APPLICAPABILITY

The invention is useful to provide a PDP improved in dischargecharacteristics such as discharge probabilities and discharge delay toprovide satisfactory discharge characteristics.

1. A plasma display panel equipped with a front substrate and a back substrate facing each other across a discharge space, and with, between the front substrate and the back substrate, a plurality of row electrode pairs and a plurality of column electrodes extending in a direction intersecting the row electrode pairs to form unit light emitting areas in the respective portions of the discharge space corresponding to the intersections with the row electrode pairs, characterized by providing: on an area facing the unit light emitting area between the front substrate and the back substrate, a magnesium oxide layer that includes a magnesium oxide crystal causing a cathode-luminescence emission having a peak within a wavelength range of 200 nm to 300 nm upon being excited by electron beams.
 2. The plasma display panel according to claim 1, wherein the magnesium oxide crystal is a magnesium oxide single crystal produced by a vapor-phase oxidation technique.
 3. The plasma display panel according to claim 1, wherein the magnesium oxide crystal causes a cathode-luminescence emission having a peak within a range from 230 nm to 250 nm.
 4. The plasma display panel according to claim 1, wherein the magnesium oxide crystal has a particle diameter of 2000 or more angstroms.
 5. The plasma display panel according to claim 1, wherein the magnesium oxide layer is formed on a dielectric layer covering the row electrode pairs.
 6. The plasma display panel according to claim 1, wherein the unit light emitting area is divided into a first light emitting area for causing light emission for forming an image and a second light emitting area for initiating a discharge for selecting the first light emitting area to cause the light emission for forming the image, and the magnesium oxide layer is provided in an area facing the second light emitting area of the unit light emitting area.
 7. The plasma display panel according to claim 2, wherein the magnesium oxide single crystal is a magnesium oxide single crystal having a cubic single-crystal structure.
 8. The plasma display panel according to claim 2, wherein the magnesium oxide single crystal is a magnesium oxide single crystal having a cubic polycrystal structure.
 9. The plasma display panel according to claim 2, wherein the magnesium oxide single crystal has a particle diameter of 500 or more angstroms.
 10. The plasma display panel according to claim 2, wherein the magnesium oxide single crystal has a particle diameter of 2000 or more angstroms.
 11. The plasma display panel according to claim 1, comprising a dielectric layer covering either the row electrode pairs or the column electrodes, and a protective layer covering the dielectric layer, wherein the magnesium oxide layer, which includes the magnesium oxide crystal causing a cathode-luminescence emission having a peak within a wavelength range of 200 nm to 300 nm upon being excited by electron beams, constitutes the protective layer of a lamination structure, together with a thin-film magnesium oxide layer formed by vapor deposition or spattering.
 12. The plasma display panel according to claim 11, wherein the thin-film magnesium oxide layer is formed on the dielectric layer, and the magnesium oxide layer including the magnesium oxide crystal is formed on the thin-film magnesium oxide layer.
 13. The plasma display panel according to claim 11, wherein the magnesium oxide layer including the magnesium oxide crystal is formed on the dielectric layer, and the thin-film magnesium oxide layer is formed on the magnesium oxide layer including the magnesium oxide crystal.
 14. The plasma display panel according to claim 11, wherein the magnesium oxide layer including the magnesium oxide crystal and the thin-film magnesium oxide layer are individually formed on the entire surface of the dielectric layer.
 15. The plasma display panel according to claim 11, wherein the thin-film magnesium oxide layer is formed on the entire surface of the dielectric layer, and the magnesium oxide layer including the magnesium oxide crystal is formed in a position opposite to a part of the surface of the dielectric layer.
 16. The plasma display panel according to claim 15, wherein the magnesium oxide layer including the magnesium oxide crystal is formed on a portion facing either the row electrode pair or the column electrode.
 17. The plasma display panel according to claim 15, wherein the magnesium oxide layer including the magnesium oxide crystal is formed on a portion excepting a portion facing either the row electrode pair or the column electrode.
 18. A method of manufacturing a plasma display panel equipped with a front substrate and a back substrate facing each other across a discharge space, electrodes formed on at least one of the front and back substrates, a dielectric layer covering the electrodes, and a protective layer covering the dielectric layer, characterized by having: a process of forming a magnesium oxide layer that includes a magnesium oxide crystal causing a cathode-luminescence emission having a peak within a wavelength range of 200 nm to 300 nm upon being excited by electron beams, in a position covering a required portion of the dielectric layer.
 19. The method of manufacturing the plasma display panel according to claim 18, wherein in the process of forming the magnesium oxide, a coating of a paste including the magnesium oxide crystal is applied to a required portion of the dielectric layer to form the magnesium oxide layer.
 20. The method of manufacturing the plasma display panel according to claim 18, wherein in the process of forming the magnesium oxide, a powder of the magnesium oxide crystal is sprayed and deposited on the dielectric layer to form the magnesium oxide layer.
 21. The method of manufacturing the plasma display panel according to claim 18, wherein the magnesium oxide crystal is a magnesium oxide single crystal produced by a vapor-phase oxidation technique.
 22. The method of manufacturing the plasma display panel according to claim 18, wherein the magnesium oxide crystal causes a cathode-luminescence emission having a peak within a range from 230 nm to 250 nm.
 23. The method of manufacturing the plasma display panel according to claim 18, wherein the magnesium oxide crystal has a particle diameter of 2000 or more angstroms.
 24. The method of manufacturing the plasma display panel according to claim 21, wherein the magnesium oxide single crystal is a magnesium oxide single crystal having a cubic single-crystal structure.
 25. The method of manufacturing the plasma display panel according to claim 21, wherein the magnesium oxide single crystal is a magnesium oxide single crystal having a cubic polycrystal structure.
 26. The method of manufacturing the plasma display panel according to claim 21, wherein the magnesium oxide single crystal has a particle diameter of 500 or more angstroms.
 27. The method of manufacturing the plasma display panel according to claim 21, wherein the magnesium oxide single crystal has a particle diameter of 2000 or more angstroms.
 28. The method of manufacturing the plasma display panel according to claim 18, wherein, in a process of forming the protective layer, the process of forming the magnesium oxide layer is performed together with a process of forming a thin-film magnesium oxide layer by vapor deposition or spattering to form the protective layer of a lamination structure made up of the thin-film magnesium oxide layer and the magnesium oxide layer including the magnesium oxide crystal.
 29. The method of manufacturing the plasma display panel according to claim 28, wherein after the process of forming the thin-film magnesium oxide layer has been performed, the process of forming the magnesium oxide layer including the magnesium oxide crystal is performed.
 30. The method of manufacturing the plasma display panel according to claim 28, wherein after the process of forming the magnesium oxide layer including the magnesium oxide crystal is performed, the process of forming the thin-film magnesium oxide layer is performed.
 31. The method of manufacturing the plasma display panel according to claim 28, wherein in the process of forming the protective layer, the magnesium oxide layer including the magnesium oxide crystal and the thin-film magnesium oxide layer are individually formed on the entire surface of the dielectric layer.
 32. The method of manufacturing the plasma display panel according to claim 28, wherein in the process of forming the thin-film magnesium oxide layer, the thin-film magnesium oxide layer is formed on the entire surface of the dielectric layer, and in the process of forming the magnesium oxide layer including the magnesium oxide crystal, the magnesium oxide layer including the magnesium oxide crystal is formed in a position opposite to a part of the surface of the dielectric layer.
 33. The method of manufacturing the plasma display panel according to claim 32, wherein in the process of forming the magnesium oxide layer including the magnesium oxide crystal, the magnesium oxide layer including the magnesium oxide crystal is formed on a portion facing the electrode.
 34. The method of manufacturing the plasma display panel according to claim 32, wherein in the process of forming the magnesium oxide layer including the magnesium oxide crystal, the magnesium oxide layer including the magnesium oxide crystal is formed on a portion excepting a portion facing the electrode. 